Resonant system support

Abstract

An oscillator producing vibrations at an operating frequency near, but different from, the resonant frequency of a resonant system is coupled to its input and the resonant system is supported a predetermined distance from its free ringing node(s) at position(s) corresponding to the effective node(s) for the operating frequency. The oscillator is controlled to maintain the operating frequency at a predetermined constant value, which keeps the effective nodes at the same position as the load driven by the output of the resonant system varies.

What is claimed is: 
     
       1. Resonant work performing apparatus comprising: a resonant system that is vibratory in a free ringing resonant mode at a resonant frequency, the resonant system having a vibratory input, a vibratory output responsive to vibrations at the input, and at least one effective node dependent in position upon the effective frequency of such input vibrations;   means for applying vibrations to the input of the resonant system at a given frequency near but different from the free ringing resonant frequency to excite the resonant system to vibration in a near resonant mode; and   a frame attached to the resonant system at the position of the effective node for said given frequency so that the transfer of vibration energy from the resonant system to the frame is minimized.   
     
     
       2. The apparatus of claim 1, in which the applying means includes means for maintaining the vibrations applied to the input of the resonant system at the given frequency as the load applied to the output of the resonant system varies, thereby maintaining the position of the node constant. 
     
     
       3. The apparatus of claim 1, in which the force applied by the vibratory input is variable to control the amplitude of the output. 
     
     
       4. The apparatus of claim 3, in which the vibratory input is an eccentric weight oscillator having replaceable weights to vary the force applied by the oscillator. 
     
     
       5. The apparatus of claim 1, in which the resonant system is a distributed mass-spring system. 
     
     
       6. The apparatus of claim 5, in which the distributed mass-spring system is a straight beam resonant in a free-free transverse mode, the input being at one end of the beam, the output being at the other end of the beam, and two nodes being spaced apart between the ends of the beam. 
     
     
       7. The apparatus of claim 1, additionally comprising a tool and means for mounting the tool on the frame for reciprocation adjacent to the output of the resonant system.